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SubjectRe: [GIT PULL] sched/core for v2.6.32
On Sun, 13 Sep 2009, Mike Galbraith wrote:

> On Sun, 2009-09-13 at 00:07 +0200, Jesper Juhl wrote:
> > On Sat, 12 Sep 2009, Ingo Molnar wrote:
> >
>
> > > It was a statistical property based on performance considerations -
> > > and now we flipped it around based on latency and for kbuild
> > > performance/throughput reasons: Serge Belyshev reported a 7%
> > > increase on a quad due to this change and i measured a 1.5%
> > > peak-kbuild performance increase.
> > >
> > Impressive. I wouldn't have expected that much gain by running the parent
> > first. Actually I personally would have expected child-first to perform
> > better since (in my experience) it's usually the child that's just forked
> > that matters the most.
>
> How can waiting for child1 to run a bit before forking off child2 _not_
> hurt? The parent is the worker bee creator, the queen bee if you will.
> Seems to me that making the queen wait until one egg hatches and ages a
> bit before laying another egg is a very bad plan if the goal is to have
> a hive full of short lived worker bees.
>
When I wrote the above, I was thinking of one specific case; a server that
receives a request, forks off a child to handle the request and the
performance we measure is of how long it takes to handle that single
request - and in that specific scenario we want the child to run as soon
as possible.

--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Plain text mails only, please http://www.expita.com/nomime.html
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html



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